1. Field of the Invention
The present invention in one aspect relates to a tool, and in one aspect, to a drill bit with projections on the bit shank to interlock with surfaces of a drill chuck to reduce the tendency of the bit to slip in the drill chuck. In another aspect, the present invention relates to a driver tool, and more particularly, to a ball hex key for engaging various sockets, the key having projections on the portions thereof that engage a socket to interlock with the inner surface of the socket to reduce the tendency of the socket to slip off of the key. In still yet another aspect, the present invention relates to a size adaptor for a driver tool, the adaptor having projections on portions thereof that join other tools, to interlock with engaging surfaces of the other tools to reduce the tendency of the adaptor and tool to separate.
2. Brief Description of Related Art
Tools having removable bits for engaging and driving various fasteners into a workpiece are known. For example, screwdrivers that have interchangeable, removable bits are known. The prior art is dominated with hexagonal driver bits modified with various fasteners to be used in an appropriately modified bit holder. A clearance is provided between the holder and the driver bit to allow ease of insertion and changing of the bit. Various retention methods that rely on interference fits e.g., rubber O-rings, etc., or mechanical locking mechanism (snap rings, etc.), or magnetic attraction are currently used, but are subject to failure due to breakage, loss of parts, magnetic weakening and wear to the inner surfaces of the bit holder.
U.S. Pat. No. 4,209,182 issued to Sheldon discloses an axially movable sleeve retained in the bore of a portable rotary housing, disposed around a spindle to hold captive a ball key which releasably retains a screwdriver bit. The sleeve is retained in the housing by a spring retainer (or the like), whereby the bit (and the retainer) may be removed and replaced by axial displacement of the sleeve. Two patents from Habermehl et.al., U.S. Pat. Nos. 5,351,586 and 5,531,143 disclose a screwdriver with a replacement bit assembly, where the bit is secured to a mandrel that is axially slidable in a socket in the end of the mandrel. These patents teach a split-ring on the bit which serves to retain the bit in the socket.
Driver tools are also known in the art. For example, socket drivers are known to employ a displaceable ball bearing retaining mechanism to hold a plurality of sockets on the driver. However, such mechanism are also prone to wear, which can render the retaining mechanism ineffective. Similar driving devices having both male driving portions (e.g., hex keys, Allen(trademark) wrenches, etc.) and female driving portions (e.g., socket wrenches, etc.) are known, but each suffered from the aforementioned problems associated with screwdriver bits.
Thus, although the prior art discloses various bit and driver retention mechanisms, none of the prior art provides a bit retention mechanism that can be used with standardized holders. Also, prior art devices suffer because there is the need to create complicated retention mechanisms and holders that can break, wear, or are expensive to manufacture.
Accordingly, the present invention solved the aforementioned drawbacks by providing a tool bit with a plurality of engaging projections that are formed within the standard geometric envelope of the shank of the bit, to permit the bit to be manufactured to standard dimensions.
Included in one preferred embodiment is a drill bit, comprising a shank portion having a geometric shape, e.g., hexagonal or circular, within a geometric envelope; and a plurality of projections formed on at least one of the sides or exterior surface of the shank and being within the geometric envelope; the projections engaging an inner surface of a bit holder or chuck to prevent slippage of the bit in the bit holder or chuck. Preferably, the projections have a triangular or sawtooth shape. Also preferably, the projections have a varying height across the surface; wherein the projections vary in height, from smallest height to biggest height, progressively across the surface.
Advantageously, the drill bit of the present invention has projections on the bit shank that engage the inner surface of the bit holder when torque is applied to the bit thereby preventing slippage of the bit in the chuck. Also advantageously, the shank with projections of the present invention can be manufactured to the tolerances of a conventional drill bit shank so that the bit can be stored in a standardized graded drill bit holder.
In another embodiment, a ball hex key is provided for engaging various sockets, the key having projections (as described above in reference to the first embodiment) on at least the portion thereof that engages a socket. Advantageously, the key provides projections to interlock with the inner surface of the socket to reduce the tendency of the socket to slip off of the key. Also advantageously, the key of the present invention can be manufactured to the tolerance of standard sockets, so that the key can be used within any standard socket.
In yet another embodiment of the invention, a driver size adaptor has projections (as above described) on portions of the surface thereof that engages or joins other tools, to interlock with engaging surfaces of the other tools to reduce the tendency of the adaptor and the tools to separate.
Although the following Detailed Description will proceed with reference being made to preferred embodiments, the present invention is not intended to be limited to these preferred embodiments. Rather, the present invention is of broad scope and is intended to be limited as only set forth in the accompanying claims.
Other features and advantages of the present invention will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals depict like parts, and wherein: